CHAPTER FOUR
BOILING
Boiling is vital to making beer. First, it allows the brewer to be sure that the liquid that they’re creating is virtually microbe-free. Very few microbes can survive a boiling. Later on, when brewers add a very specific organism into the liquid, they want to be sure what they are adding is the only one in there.
Boiling provides a means for driving off some volatile off-flavors that can derive either from the ingredients or from certain chemical reactions that happen in wort when heat is added. A good rolling boil allows the brewer to remove some chemicals that would otherwise be unpleasant in the finished product.
Hops must be boiled in order for them to go through the isomerization process. Boiling is also how hop oils are efficiently extracted into wort, providing both bitterness and hop flavor and aroma. Finally, boiling provides caramelization, sometimes in light amounts and sometimes in greater ones, offering an enjoyable, rich complexity to your beer, which pairs beautifully with roasted or grilled foods.
Problems in the boil usually derive from poor temperature control or measurements—both of which can be solved through careful attention to the necessary processes.
35 | My boil has long stringy debris in it |
CAUSE
As wort boils, proteins and carbohydrates coagulate, making long stringy-looking protein chains. This is known as “hot break” and occurs with varying intensity, depending on wort composition and temperature
SOLUTION
Hot break in and of itself is not a problem, though it can appear to be one when first experienced. A lot of hot break can often lead to a clearer beer in the end, because as proteins stick together, they settle out of solution and are less likely to be passed along to fermentation.
To avoid an excessive amount of hot break, cut down on protein content in your wort. This will often come in the form of high-protein adjuncts, such as wheat or rye, but can also be present in some barley. Six-row barley has a higher protein content than two-row barley, and even among those, different batches of malted barley may have higher protein content than others. Ask at your local homebrew store if they have spec sheets, provided by the maltster, with details of protein content.
Hot break isn’t something you necessarily need to avoid or fix, it is just something that you want to avoid bringing into your finished wort. In order to help hot break settle out of solution, use a fining agent, such as Irish moss or Whirlfloc, to help further coagulate the proteins.
At the end of a boil, stir the wort in your pot into a whirlpool and allow the whirlpool to settle before transferring wort into your fermentation vessel, siphoning wort from the edge of the pot, leaving all the settled proteins, carbohydrates, hops, and whatever else you put into your boil in the center pile of trub.
A good rolling boil has many benefits; for example: caramelization, evaporation, isomerization, sterilization, and driving off unwanted off-flavors.
36 | My boil ended prematurely |
CAUSE
The power went out, the propane tank emptied, or something else unplanned happened to cause the boil to end prematurely.
SOLUTION
Recovering from a loss of active heat in the middle of a boil can be really tricky, but not impossible.
First, make note of how long the wort was boiling to best make decisions.
• Less than 10 minutes: your wort has pasteurized, but not necessarily sterilized. Hops have not had a chance to isomerize and create bitterness. Off-flavors may remain. Find a way to resume boil, and boil again for 60 minutes.
• 10–30 minutes: your wort has been sterilized and some isomerization has occurred. The beer will not be as bitter as planned, and may be missing some planned caramelization qualities. If resuming boil at some point soon is possible, do so. You may consider adding late-addition hops and steeping before cooling.
• 30–45 minutes: wort has been sterilized and most isomerization has occurred. The beer will not be quite as bitter as planned, but it may not be a detectable change, depending on the style. Pitch late-addition hops, cool the wort, transfer to fermenter, and pitch yeast.
• 45–60 minutes: you can consider this boil complete and proceed as normal.
There are instances of “no-boil” or “raw” beers made by some homebrewers. These are often beers soured with lactobacillus bacteria, with low alcohol content and little-to-no bitterness. Raw beers have the risk of producing off-flavors and could be subject to much different bacterial infections than beer that has been boiled. Proceed with caution if you cannot boil your beer.
Brewing outdoors on a propane burner, rather than indoors on a stovetop, can mean a significantly faster and less messy brew day. Insure that your propane gas tank is sufficiently full and in good working order before starting your boil.
37 | I don’t have enough wort |
CAUSE
At the end of a boil, the final measured volume is below what is expected. Brewer did not use enough water in lauter or steep, or experienced a higher than expected rate of evaporation.
SOLUTION
In the worst-case scenario, there is less beer than planned at the beginning of the boil, which will likely yield a higher gravity than expected at the outset.
In extract brewing, it’s common to have less wort than the final fermentation and it is even something that can be planned for as part of a “partial boil” (See Problem 70). It is typical and expected to add water to the wort to achieve the correct volume.
In all-grain brewing, if the problem was not lautering for long enough you may have a much more concentrated wort than originally planned. It is better, of course, to lauter the correct amount of liquid the first time around, as any correction will no longer produce the beer as exactly specified by the recipe, and bitterness may be affected. The best solution is to take a gravity reading once the wort has cooled and then add a small amount of distilled water. Continue taking gravity readings and adding water until the target gravity is achieved.
If the problem is that your rate of evaporation was higher than expected, you should be able to add water to achieve the target volume.
It is ultimately up to the brewer to decide whether the best course of action is to fix this problem on the fly, or just be sure to correct the next batch.
A small wort, or concentrated wort, is not necessarily a bad thing, depending on what style of beer is being made, and if you have a plan for what to do next.
38 | I have way too much wort |
CAUSE
Inaccurate measurements or inattentiveness leads to a kettle which has much more wort than anticipated, which may produce a watered-down flavor, boil-overs, or an unexpectedly low alcohol content.
SOLUTION
First, measure the gravity of the wort and compare the result to what is expected in the pre-boil gravity of the recipe. There is a chance that a very efficient mash has produced more sugar than anticipated, so gravity targets can still be hit even with a higher volume. If the liquid can fit into the kettle or into the fermenter, there is no reason to worry about additional volume.
However, if you are low on gravity, or you have limited fermenter space, the easiest solution is to boil longer to reduce the volume of your wort. Most homebrewers will see an hourly evaporation rate of 6 to 8 percent. If you have seven gallons in the kettle, and your goal is to achieve five, you may need to boil up to two-and-a-half hours or longer. Be sure to have a means of measuring liquid within the kettle (see Problem 78) and measure frequently throughout the boil, bearing in mind that boiling liquid takes up more space than non-boiling liquid.
Remember that hop additions are generally documented in the “time before the end of the boil” notation of a recipe. If you are boiling for an additional time, you may want to wait before your initial hop addition to avoid excessive bitterness.
Bear in mind that longer boil times will lead to more caramelized wort, meaning a darker beer with a higher portion of unfermentable sugars and in some cases a more caramel character. Some styles, like Scottish ales, are brewed in this manner on purpose, but most are not.
Avoid boil-overs by insuring your brew pot is large enough to hold your wort plus an extra 25 percent of space. Wort takes up more space when it’s boiling. Depending on the gravity reading, an excess of wort can be reduced by boiling for a while longer, but this might cause unwanted flavors in the final beer.
39 | After boil my beer won’t cool down fast enough |
CAUSE
Inefficient heat exchange may mean long cooling times, reducing cold break, leading to a cloudier beer, and increasing the risk of DMS formation or contamination.
SOLUTION
The first method that most homebrewers learn to cool their wort is to rest their kettle in a cold-water bath, which helps draw the heat of the wort into the water, thereby cooling the wort. This can be an effective means of cooling homebrew, but can often feel a bit labor-intensive. When a kettle is submerged in a water bath, heat is transferred directly to the water around the kettle. However, once that water gets warm, it can no longer transfer as much heat, so the water on the outside of the kettle must be kept in motion to continually bring new, cool water in contact with the kettle. At the same time, the wort on the outside of the kettle cools first, meaning the hot wort in the center must be moved out toward the sides of the kettle. The water-bath method is usually fastest when both the wort and the water bath are being stirred.
In some warmer climates, heat exchangers such as copper-coil exchangers or plate chillers may be inefficient due to the ambient groundwater temperatures. Although an additional expense, a second heat exchanger may be the best solution. It can be used additionally to cool wort or even to cool the water on the way to the heat exchanger by using an ice bath or other cooling method on the secondary heat exchanger.
An ice bath is a simple and cheap method for cooling wort. If using an ice bath, keeping the liquid inside moving will insure that the cooling process is quicker and more efficient.
40 | I keep having boil-overs |
CAUSE
During boil, proteins in the wort form a dense foam that is lifted by gas escaping the liquid, causing liquid to boil over the side of the kettle.
SOLUTION
The most cost-effective way of avoiding boil-overs is temperature control, and manually breaking surface tension with a spoon or other stirring device. Stirring the foam back into the liquid can often help stop it from boiling over the side. Alternatively, quickly lowering the temperature (or removing the kettle from direct heat) can reduce the amount of gas escaping and stop the wort from boiling over.
Always be careful when adding hops. Adding hops before the wort comes to a boil can sometimes add enough hop oil to help break the surface tension that causes boil-overs. However, adding hops after the boil has begun can often create a layer of hops that acts much the same as the layer of foam at the beginning of a boil, and can cause boil-overs.
A chemical additive called Fermcap is available to homebrewers. It is a silicone-based emulsion that works by breaking surface tension in the boil. If usage rate is too high (over 10 percent of volume), then it can lead to residual bitterness in beer, but used correctly it has no effect on the end product.
Finally, if boil-overs are a frequent problem, you may consider purchasing a larger kettle to brew in, or brewing concentrated wort (see Problem 70). Concentrated wort can still boil high, even more than normal-strength wort, but there will be more room in your kettle.
Boil-overs are not just a waste of wort, and therefore a waste of beer. They can also be very dangerous, as boiling, sugar-filled water splashes and erupts over the surrounding surfaces.
41 | I forgot to add my hops |
CAUSE
Forgetting to add hops on time may lead to a general lack of hop flavor (overly sweet or lack of bitterness). Hops are an active anti-bacterial so, if not added at all, there is a slightly increased risk of infection and shorter shelf-life.
SOLUTION
If the boil has not yet ended, there is still time to add hops. Hops added close to the time listed in the recipe should be “close enough” for most cases. There will be a slight difference in isomerization and hop utilization, but not enough to be detected by the majority of drinkers in a side-by-side comparison with another batch of the same beer.
If the addition time has passed by more than 10 minutes, then you must decide whether you are okay with less hop bitterness/less hop flavor. If not, consider resetting the timer on the boil from that point. If you’ve missed your 45-minute addition and it is not time for your 15-minute addition, make the addition and time 45 minutes for the rest of the boil. This will cause additional bitterness contributed by the previous hop additions.
If the boil has ended, there are two options. Hops are vital for beer to taste like beer, and they need to be boiled to create bitterness. You may boil hops in a small amount of water for the desired time (e.g., 60 minutes, 45 minutes) and add the resulting liquid to the fermenter after it has been cooled.
The last option is simply to add the hops as a dry-hop addition. In this case hop flavor and hop aroma will be added (though different in character from boiled hops), but bitterness will not.
Hops are an important addition to a brew due to their anti-bacterial properties. If a brewer forgets to add them at the time stated on the recipe, there are options available to rectify this, but the final beer will likely end up different from what was originally intended.
42 | I added more hops than I was supposed to |
CAUSE
Inaccurate measures, or a simple mistake, leads to more hops being added at a particular time addition than was called for in a recipe.
SOLUTION
If the boil has already ended, there is nothing you can do to remedy this issue. You now have a beer that will have a more bitter, hoppy flavor or aroma.
If the boil is still going, there is a decision to be made: go ahead with the higher bitterness derived from the hop addition (i.e., do nothing and see how it turns out) or adjust the rest of the beer going forward. There are two possible adjustments to be made, and they can be made together or separately.
First, you can reduce the boil time. Since more alpha acids isomerize the longer the boil lasts, if you reduce the boil time, you can reduce the bitterness derived from the hop addition. However, there will be a certain amount of extra hop character in the beer regardless, and you may also run the risk of not completely driving off potential off-flavors during the boil.
Second, you can choose to reduce later hop additions. Since all hop additions add a certain amount of bitterness to the wort, reducing late hop additions can help you keep bitterness in check, though you will do so at the risk of flavor and aroma characteristics.
You may choose to reduce the boil time but add later additions at their full amounts, thereby reducing bitterness from boiling but retaining later hop characteristics.
Ultimately, this is one of the many cases where brewing is an art as much as a science and the decision about how to deal with a circumstance is in the brewer’s creative hands.
Adding hops is as simple as dropping pellets into the brew. Do so carefully, however, as adding hops too quickly may sometimes lead to boil-overs.